An ethylene-vinyl alcohol copolymer, which henceforth may be abbreviated as EVOH, is superior in transparency and gas barrier property, but it has defect of being poor in stretchability, flexibility and flexing resistance. Known is a method of blending a flexible resin such as an ethylene-vinyl acetate copolymer and an ethylene-propylene copolymer to an EVOH to improve the defect. However, this method has a defect that the transparency deteriorates greatly.
On the other hand, JP-A-63-230757 discloses a resin composition comprising 94-30 parts by weight of EVOH (A) having an ethylene content of 20-45 mol % and a degree of saponification of 96 mol % or more and 6-70 parts by weight of EVOH (B) having an ethylene content of 24-49 mol % and a degree of saponification of less than 96 mol %, wherein the ethylene content of (B) is greater by at least 4 mol % than that of (A) and the degree of saponification of (A) is greater by at least 3 mol % than that of (B) and wherein the ethylene contents and solubility parameters of (A) and (B) satisfy a specific relation. This resin composition is reported to be superior in heat high-speed stretchability.
JP-A-50-12186 discloses a method for producing a modified EVOH with an improved mold-workability, the method being characterized by reacting 0.01-0.8 parts by weight of polyfunctional epoxy compound with 100 parts by weight of EVOH having an ethylene content of 20-90 mol % and a degree of saponification of 95% or more. This published specification also discloses that such a modified EVOH can be mixed with the other resins such as unmodified EVOH and polyolefin.
However, in a method of blending a soft resin other than EVOH to EVOH, it is difficult for a resulting resin composition to have satisfactory stretchability, flexibility and flexing resistance and satisfactory transparency simultaneously. In addition, the gas barrier property is also deteriorated. Moreover, the resin composition disclosed in the above-cited JP-A-63-230757 does not necessarily have satisfactory flexibility or satisfactory flexing resistance.
In JP-A-50-12186, an improvement in neck-in (a phenomenon that a product width becomes narrower than die slit width) which occurs when an EVOH is shaped into a film through a T-die is disclosed as an improvement in mold-workability. However, there is no description about the improvement in stretchability, flexibility and flexing resistance, which is the object of the present invention. Moreover, the EVOH resulting from a reaction with a specific amount of multifunctional epoxy compound or a resin composition containing the same, which are disclosed in the above-cited publication cannot demonstrate effects of improving stretchability, flexibility and flexing resistance. Furthermore, in the case of using a polyfunctional epoxy compound, it is difficult to produce an EVOH whose amount of modification with an epoxy compound is within the specific range specified in the present invention.
An object of the present invention is to provide a resin composition superior in barrier properties, transparency, stretchability, flexibility, flexing resistance and interlayer adhesiveness and a barrier material comprising the same. In addition, the present invention intends to provide various types of molded articles comprising such a resin composition.